Eskimos with enough skill can build igloos in two hours. Inexperienced adults usually find it difficult, if not impossible, to build one. The usual igloo is dome-shaped and is made of rectangular blocks of compact snow. Instead of molding or pressure-forming the blocks of snow, Eskimos cut out rectangular blocks off of a compacted mass of snow using a saw-like cutting tool. It requires a lot of skill to build a dome-shaped structure out of rectangular blocks of snow. The shape of the blocks changes slightly from one row of blocks to the next because the top edge of a row of blocks has to incline towards the center of the structure. The higher the wall, the greater this angle of inclination with respect to the ground, and the more difficult it is to lay the next row of blocks. Also, the spherical wall itself has to curve inwards as it is built towards the top.
U.S. Pat. No. 2,682,235 was granted to Buckminster Fuller in 1954 for geodesic domes. A geodesic dome is a structure derived from about half of a geodesic sphere. The surface of a geodesic sphere is made up of vertices, edges, and planes. The edges define triangular planes, and each vertex is a meeting of either 5 or 6 edges. A vertex that connects 5 edges is the center of a pentagon, and a vertex that connects 6 edges forms the center of a hexagon. Looked at this way, there are always 12 pentagons around a geodesic sphere. In the geodesic igloo there are only 6 pentagons because it is approximately a hemisphere.
The geodesic igloo (hereafter referred to as a bucky igloo) can be constructed easily using the molds described in this invention.
The bucky igloo requires only 6 pentagons, 10 full hexagons, and 5 half hexagons. This corresponds to Fuller's icosahedron with a frequency of 3. An igloo with the shape of an icosahedron with a frequency of 6 can be built with the same molds described here. However, building such igloo can be very challenging because much more blocks are required and each hexagon is not exact.
Reference: "A Fuller Explanation: The Synergetic Geometry of R. Buckminster Fuller", by Amy C. Edmondson, Birkhauser Boston, 1987.